My gauge on my dash has ---F degrees. It's never done that before. What should I do or what needs to be replaced because now I don't know how hot my car is running.

Thanks,

Trey

 

Emmisions engine light just came on also about 10 mins (guessing) after i noticed my coolant temp wasnt showing.

 

Mine just did that last night, first time ever. Came back on today, but still going to replace coolant temp sensor which is located on the backside of the block driver side.

Pics: https://www.cobaltss.net/forums/2-2l...sensor-237518/

 

could just be a loose connection, corosion, short or open in the circuit. if anything else that could be in that circuit is acting up, id bet on that.

 

Had the ---F on both of my POS Cobalts, warrenty replaced the cooling sensor

 

Don't rule out the thermostat. The exact same thing happened with me on my 2.4.
Before The check eng light came on, i went ahead and slapped a ECT sensor in in between cars that I was working on. Didnt fix a thing.
Then I actually did was I am paid to do...diagnose. After checking over everything, It ended up being a thermostat.

You need to see what code was set and go from there.
If the thermostat code was set; Low coolant, thermostat stuck/leaking, coolant temp sensor could be the causes of the code to set.

 

Ok. So would the coolant sensor make the emissions engine light come on?? But u guys r saying the two things could be that sensor or the thermostat. How much would those be

 

I wish I could tell you but both times the bill when either car was picked up had all zero's on it stating warrenty work

 

The flat line is a common issue that often points to a bad thermostat. Replace it. It costs like 30 bucks for the stat/coolant and takes 45 minutes if you do it yourself. Or bring it in if you're still under warranty and let the dealer resolve it.

 

ok, so i looked at autozone and they have the thermostat and coolant sensor and both are $23.99. Is there a way to test which one it is for sure. My stepdad says it is the thermostat but i want to make sure b4 i spend the money. Thanks for all the replies guys. I was nervous. This is my first car and i didnt want anything to happen to it.

 

If you do get the sensor/thermo; make sure you get a delco...

To test the ECT sensor; You need to use a scan tool that allows you to look at things like: TPS, ECT, O2 voltages...I am partial to thee Snap-On Solus
Or use an interceptor

To Test the wiring, unplug the sensor while you are watching the scan device, and you should see the minimum like -40ş and take a jumper wire and jump the pigtail and you should see the max temps roughly 275ş...You are just looking for the MIN/MAX to verify the wiring.

And while watching the scan tool/interceptor with the engine running, watch the temps from cold->hot and if the sensor is good, it should have a consistent and relatively steady increase

 

So the duralast thermostat from autozone wouldnt work?

 

Thermostat took a ****

 

mindrot, is that what your saying happened to my car or you saying the duralast thermostat is ****?

 

Stick with factory ****; the delco has a much better chance of being properly manufactured and to work properly.

 

I remember that my temp gauge would always go up to 203 degrees b4 it would cool back down to 190. Could that have been a sign that the thermostat was goin out

 

That is exactly what mine was like; over time the running temps would slowly get hotter.

When I changed out the thermostat the running temps went from 198 to the current running temp of 180 and it occasionally will jump to 185 if I'm in traffic.

 

Problem fixed. It was the thermostat. Thanks guys

 

I should be a little more descriptive next time lol. I meant that your Thermostat took a crap on you. Always stick with OEM imo. I'm happy to hear it's fixed now. I know how annoying it can be.